Separation of variables of a spherically symmetric Dirac Hamiltonian
in dimension 3
is described in many texts and belongs to the standard curriculum of
relativistic quantum mechanics [1]}.
Of course, it is even more
straightforward to solve a rotationally symmetric Dirac Hamiltonian in
dimension 2. However, to our knowledge, the first treatment
in any dimension is due to Gu, Ma and Dong [2]}.
